Episodes IV, V, VI

Episode I

Episode II

Anakin face-planting, falling down during a lightsaber battle, and spitting out overly hot soup.

Episode III

There was "Nooooooooooo!" official blooper reel for Episode III, so some YouTube person cut together behind-the-scenes footage of wacky stuff. My favorite? C-3PO falling down unintentionally, and Samuel L. Jackson falling down intentionally.